The side group of arginine is protected by which of the following protecting groups?

• A. A triphenylmethyl group (Trt)
• B. A tertiary butyl group (tBu)
• C. A tertiarybutyloxycarbonyl (tBOC)
• D. 2,2,5,7,8-pentamethylchroman-6-sulphonyl group (PMC)